Hess's law is used to calculate the enthalpy of a reaction by adding the enthalpies of intermediate reactions together. This is based on the principle that the total enthalpy change of a reaction is independent of the path taken.

Here are the steps to use Hess's law:

1. Identify the initial and final reactions in the reaction path. The initial reaction is the starting point, and the final reaction is the desired reaction.

2. Find the enthalpy change (∆H) for each intermediate reaction. This can be obtained from tables in chemistry textbooks or online databases.

3. Add up the enthalpy changes of the intermediate reactions. According to Hess's law, the sum of these enthalpy changes equals the enthalpy change of the overall reaction.

4. If the final equation in the reaction path is not the desired reaction, you may need to manipulate the intermediate reactions (reverse them or multiply them by a coefficient) so that they add up to the desired reaction. The enthalpy changes of these manipulated reactions should also be reversed or multiplied by the same coefficient.

5. The sum of the enthalpy changes of these manipulated reactions gives the enthalpy change of the desired reaction.

So, the correct answer is A. The desired enthalpy is obtained through adding intermediate reactions together.

Question

Hess's law is used to calculate the enthalpy of a reaction by adding the enthalpies of intermediate reactions together. This is based on the principle that the total enthalpy change of a reaction is independent of the path taken.

Here are the steps to use Hess's law:

1. Identify the initial and final reactions in the reaction path. The initial reaction is the starting point, and the final reaction is the desired reaction.

2. Find the enthalpy change (∆H) for each intermediate reaction. This can be obtained from tables in chemistry textbooks or online databases.

3. Add up the enthalpy changes of the intermediate reactions. According to Hess's law, the sum of these enthalpy changes equals the enthalpy change of the overall reaction.

4. If the final equation in the reaction path is not the desired reaction, you may need to manipulate the intermediate reactions (reverse them or multiply them by a coefficient) so that they add up to the desired reaction. The enthalpy changes of these manipulated reactions should also be reversed or multiplied by the same coefficient.

5. The sum of the enthalpy changes of these manipulated reactions gives the enthalpy change of the desired reaction.

So, the correct answer is A. The desired enthalpy is obtained through adding intermediate reactions together.

Knowee AI · Accepted Answer

Hess's law is used to calculate the enthalpy of a reaction by adding the enthalpies of intermediate reactions together. This is based on the principle that the total enthalpy change of a reaction is independent of the path taken.

Here are the steps to use Hess's law:

1. Identify the initial and final reactions in the reaction path. The initial reaction is the starting point, and the final reaction is the desired reaction.

2. Find the enthalpy change (∆H) for each intermediate reaction. This can be obtained from tables in chemistry textbooks or online databases.

3. Add up the enthalpy changes of the intermediate reactions. According to Hess's law, the sum of these enthalpy changes equals the enthalpy change of the overall reaction.

4. If the final equation in the reaction path is not the desired reaction, you may need to manipulate the intermediate reactions (reverse them or multiply them by a coefficient) so that they add up to the desired reaction. The enthalpy changes of these manipulated reactions should also be reversed or multiplied by the same coefficient.

5. The sum of the enthalpy changes of these manipulated reactions gives the enthalpy change of the desired reaction.

So, the correct answer is A. The desired enthalpy is obtained through adding intermediate reactions together.

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